Aiming arrangement for grenade throwers

ABSTRACT

A device for automatically setting the elevation angle of the aiming attachment of a grenade launcher in response to adjusting the range scale to the desired range. The range scale is on the surface of a casing mounted on the launcher tube for rotation adjustment. A sleeve extends over the scale indicia to protect the indicia and has a viewing window with a hairline to permit accurate adjustment of the range scale casing. A cam at the end face of the casing cooperates with a follower on the support shaft of the aiming device to adjust the angular setting of the aiming device in response to setting the range scale. The range scale casing is rotatably supported by a clamp sleeve which connects the bipod to the upper end of the launcher tube. With the aiming device angle preset by adjusting the range scale, it is a simple matter to adjust the bipod to position the launcher tube at an elevation angle to fire a projectile the required range.

United States Patent r 1 Asikainen Jan. 16, 1973 541 AIMING ARRANGEMENT FOR GRENADE THROWERS [75] Inventor: Niilo Kalervo Asikainen, Tampere,

Finland [73] Assignee: 0y Tampella Ab, Tampere, Finland [22] Filed: Dec. 8, 1970 [21] Appl. No.: 96,060

[30] Foreign Application Priority Data Dec. 12, 1969 Germany ..P 19 62 339.3

[52] 11.8. CI. 89/4l B, 33/235, 89/37 C, 89/41 E [51] Int. Cl..; ..F41g 3/14 [58] Field of Search.....89/1 F, 11,37 C, 40 A, 41 B, 89/41 E; 33/48, 235

[56] References Cited UNITED STATES PATENTS 3/1920 Stokes"; ..89/lJ 3/1959 Gabrusti ..33/48 Primary Examiner-Stephen C. Bentley AttarneyMarkva, Smith & Kruger [57] ABSTRACT A device for automatically setting the elevation angle of the aiming attachment of a grenade launcher in response to adjusting the range scale to the desired range. The range scale is on the surface of a casing mounted on the launcher tube for rotation adjustment. A sleeve extends over the scale indicia to protect the indicia and has a viewing window with a hairline to permit accurate adjustment of the range scale casing. A cam at the end face of the casing cooperates with a follower 0n the support shaft of the aiming device to adjust the angular setting of the aiming device in response to setting the range scale. The range scale casing is rotatably supported by a clamp sleeve which connects the bipod to the upper end of the launcher tube; With the aiming device angle preset by adjusting the range scale, it is a simple matter to adjust the bipod to position the launcher tube at an elevation angle to fire a projectile the required range.

17 Claims, 4 Drawing Figures PATENTEDJAH 16 I975 SHEET 1 BF 3 FIG. 7

INVENTOR All/L0 Afluaeo AsIKA/NEN 77mm, 5M2! yw PATENTEUJAH 16 1975 SHEET 3 BF 3 INVENTOR All/L0 km vmw AS/kA/A/EN AIMING ARRANGEMENT FOR GRENADE THROWERS This invention relates to apparatus for determining and making the angular adjustment of the aiming attachment of mortars, grenade launchers, and the like, and facilitates rapidly setting up and changing the range of the mortar.

More specifically, the invention relates to apparatus for automatically setting the elevation indicating device of the aiming attachment of a mortar or grenade launcher in response to setting the desired range on a scale located on the barrel or launcher tube and which facilitates the use and reading of the range table.

Grenade launchers, mortars and the like are aimed with the aid of a range table which indicates the required elevational angle of the barrel for firing a projectile a particular horizontal distance. The usual launcher has the bottom of its barrel supported on a base having a cooperating socket, and the upper end of the barrel is supported by an adjustable bipod or similar mount. The aiming device usually includes a sight mounted on the barrel and which is adjustable to facilitate making changes in the elevation angle and azimuth angle of the barrel. Connected to the aiming device are two spirit levels which are perpendicular to each other. When the barrel is in the usual firing position, both levels are horizontal and indicate that the barrel is properly positioned. One level has its bubble axis perpendicular to a vertical plane including the axis of the barrel.

To set up and fire the launcher, the base and the support plates for the bipod arms are first seated on the ground so the barrel of the launcher is directed along an azimuth in line with the target. After the range of the target is determined, the range table is consulted to determine the proper elevational angle of the barrel to hit the target. Next, the aiming device is set to the angle read from the range scale. Then, the bipod arms are adjusted until the bubbles of both spirit levels are centered, i.e., both levels are horizontal, and the barrel is then properly aimed.

In I the prior mortars and grenade launchers, the range table was either a separate unit which could readily be misplaced or lost, or was directly attached to the launcher, for example, to the barrel or the launcher tube. The disadvantage of this latter arrangement is that the range scale attached to the tube of the launcher is easily damaged by external forces, e.g.. a blow or the like, when the launcher is being transported. As a result, a portion of the table can be obliterated or become illegible so rapid determination of the proper settings of the sight and aiming device, especially in an emergency, is difficult if not impossible.

In accordance with this invention, the problems encountered with the prior art range table and launcher tube arrangements are eliminated. Correspondingly, an object of the invention is to so mount and arrange the range scale that it is always visible for operation of the launcher yet is protected against damage, and a range scale separate from the launcher is not required. According to this invention a device is provided for determining and making the angular setting of the aiming device so the elevation angle of the launcher barrel can be properly adjusted, the device having particular utility with a grenade thrower or launcher of the type in which the launcher barrel has an articulated mounting at its lower end, and is supported at the top end by a bipod support which is connected to the barrel by a hinged joint to a clamp sleeve that. surrounds the barrel,

and in which the aiming device is adjusted for its proper angular setting relative to the axis of the barrel by means of a casing with a range scale on its peripheral surface and mounted on the barrel for rotation. As the casing is rotated, the position of the scale relative to a hairline or other indicator is changed so the proper range can readily be set under the hairline.

By virtue of this arrangement, elevational adjustment of the sight is simply and easily accomplished and the angular setting of the sight can be read from a large range scale visible on the barrel of the launcher. By virtue of the rotating casing arrangement, the elevation angle of the sight can be precisely adjusted. Advantageously, the rotatable casing is axially elongated to provide space for the numerals of the range table of sufficient size so the range scale can easily be read. The

in the preferred embodiment, the rotatable casing on which the scale indicia are placed is threadedly received in the sleeve which is fixed to the barrel and the aiming device is supported on. the sleeve. By virtue of the threaded connection, rotating the casing permits adjusting the initial axial position of the casing very precisely and means are provided to change the angular position of the sight in response to such axial movement of the casing. Advantageously, the sleeve covers the casing except at a short handgrip part of the casing which is exposed below the casing.

The mechanical connection between the casing and sight and via which the elevational angle of the aiming device is adjusted in response to rotation of the casing, includes an axial cam formed on the upper end face of the casing and a follower secured to the support shaft of the sight and which is spring urged into engagement with the cam. By virtue of this cam arrangement, adjusting the horizontal position of the sight is accomplished for substantially 360 of rotation of the casing. Since the casing has a diameter larger than the barrel of the launcher, the cam can be made with the pitch necessary to obtain the proper angular adjustment of the sight but along a relatively long path of adjustment of the large diameter casing.

ln viewof the above it is apparent that the adjusting device according to this invention has no projecting parts which cause interference with either the operation of the launcher when in use or during transporta tion of the launcher. In addition, the device provides for precise adjustment of the elevationangle and simple operation.

Numerous other features and advantages of the invention will become apparent with reference to the accompanying drawings, which show a preferred embodiment of the invention, and in which FIG. 1 is a side view in elevation of a grenade launcher in its firing position and including the range setting device of this invention;

FIG. 2 is an enlarged fragmentary view in rear elevation of the barrel of the launcher of FIG. 1;

FIG. 3 is a side elevational view in partial section of the portion of the barrel of FIG. 2; and

FIG. 4 is a partial view in section taken along the line 4-4 of FIG. 2.

While the preferred embodiment of this invention .will now be described with reference to the grenade thrower or launcher shown in the drawings, it is to be understood that the invention also has utility with other projectile launching devices such as mortars and the like.

The grenade thrower 1 shown at FIG. 1 has a projectile launching tube 2 with a spherical shaped lower end 3. A base plate 4 has a spherical socket 5 toreceive spherical end 3 so launching tube 2 is supported on the base for pivotal movement.

The upper end of tube 2 is supported by a bipod 6 having a pair of legs 6a (only one of which is shown in FIG. 1) each of which is supported at its lower end by a support plate 6b at an articulated connection. The upper end of bipod 6 is connected toa bracket 7 which in turn is connected to lugs 8a of a clamp sleeve 8 which encircles launching tube 2. The upper end of bracket 9 is provided with suitable openingsfor connection to lugs 8a with a bolt 9. The aiming attachment 10 for the grenade launcher is mounted on clamp sleeve 8.

As shown at FIGS. 2 and 3, clamp sleeve 8 encircles launching tube 2. Secured to the lower end of the clamp sleeve is an extension sleeve 11. Extension sleeve 11 is secured to clamp sleeve 8 in any suitable manner, for example, by screws 12, as shown at FIG. 3. Formed on the i'nner surface of sleeve 11 at a location spaced below clamp sleeve 8 is a fine thread 13 of trapezoidal thread form and of only a few pitches.

A thread 14 is formed on the exterior surface of a hollow cylindrical casing 15 which is mounted on launching tube 2 for rotation. As shown at FIG. 3, casing 15 has a thin side wall and extends into the annular space between extension sleeve 11 and the outside of the launching tube, with its thread 14 in mesh with the thread l3of sleeve 11. Extending below the lower end of extension sleeve 11 is a knurled hand grip portion 15a of the casing which facilitates manually rotating the casing. 1

Formed in the lower portion of extension sleeve 11 is a generally rectangular cutout in which a transparent glass or plastic viewing window 16 is mounted and which, as shown at FIGS. 1 and 2, faces upwardly when the grenade launcher is in its firing position. Window 16 provides for viewing the outer peripheral surface of a length of casing 15, and a range table 17 is provided on this length of the casing. As will subsequently be described in detail, the range table 17 can extend around practically the entire circumference of the easing 15. At the center of viewing window 16 is a hairline indicator 16a'which provides for rapid accurate alignment of the indicia of the range table with the indicator and facilitates reading the scale. As shown at FIG. 2, there are several rows of range figures in the table 17 and these rows are arranged in line with the numerals 0, l, 2, 3, and 4 at the left side of window 16 under the letter P. These numerals indicate the required number of (or the setting of) propellant charges to propel a projectile the distance shown on the corresponding row of the scale.

Threaded onto the top end of casing 15 is a cam ring 18 having an axially facing cam face 19. Cam ring 18 is secured to casing 15 against rotation by a lock pin 20. With reference to FIG. 4, it will be seen that cam face 19 rises only slightly along the substantially 360 circumferential extent of the face.

Aiming attachment'lO is supported by a shaft 21 which extends through and is mounted for rotation in a bushing 22. Bushing 22 is secured to a flanged collar 23 which in turn is secured to the upper end of extension sleeve 11. Shaft 21 has an inner rectangular end portion 21a and a cam follower arm 24 with a mating rectangular opening therethrough is mounted on and secured to rectangular portion 21a. Cam follower arm 24 has a projecting rounded tip 24a which engages cam face 19. Tip 24a is normally urged into engagement with cam face 19 by a helically woundtorsion spring 25 located in and having one ofits endssecured to bushing 22, and having its other end bent back and extending through a bore 26 of follower arm 24. With spring 25 appropriately tensioned, tip 24a of follower arm 24 is constantly urged into engagement with cam face 19.

To limit the extent of rotation of casing 15, a stop projection 27 is provided at the respective ends of cam face 19, and rotation of the casing is limited by the engagement of tip 24a with one side of projection 27 when casing 15 is rotated in a counter clockwise direction, and by engagement of the other side of projection 27 when casing 15 is rotated in a clockwise direction. By virtue of the engagement of tip 24a of follower arm 24 with cam face 19, and by virtue of the action of spring 25 which constantly urges follower arm 24 into engagement with cam 19, it will be apparent that shaft 21, and correspondingly, aiming device 10,

are angularly adjusted relative to launching tube 2 when casing 15 is rotated.

To avoid damage to the aiming device 10 and the casing and sleeve supported by the clamp sleeve 8, the

lower end of spring 28. The body ofclamp sleeve 8 is spaced from the outer surface of launching tube 2 to provide an annular space to accommodatespring 28. At the upper end of clamp sleeve 28 is a ring 30 that presents a downwardly facing annular shoulder 31 which engages the upwardly facing transverse annular shoulder of a projecting ring portion 32 of the launcher tube. Spring 28 has its lower end seated on the upwardly facing seat 29 and its upper end seated against the downwardly facing surface of ring portion 32. Spring 28 therefore exerts a downwardly directed force on clamp sleeve 8 to normally maintain shoulder 31 against the top surface of ring portion 32 of the launching tubebut allows the launcher tube to move axially downwardlyrelative to the clampsleeve 8 when the thrower 1 is fired, so clamp sleeve 8 and its associated parts will not be damaged by recoil. Spring 28 does of course return the sleeve to its proper position on the launching tube, after the recoil, so the parts return to their initial positions as shown at FIG. 3.

retaining Aiming device includes an apertured sight 33 mounted for rotation about a horizontal axis on ears 33a so the sight can be pivoted in a vertical plane by manipulating thumbpiece 34 regardless of the angular position of shaft 21. Also mounted on aiming device 10 are spirit levels 35 and 36. The level 36 has its axis in a vertical plane parallel to the axis of the launcher tube 2. The vertical plane in which the axis of level 36 moves when shaft 21 is rotated is perpendicular to the shaft. Level 36 provides means for accurately setting the angle of elevation of the launching tube. Level 35 has its axis parallel to shaft 21 and is in a plane perpendicular to the vertical plane in which the axis of launcher tube 2 lies. Both levels are secured to the aiming device. The angle of inclination of level 36 is changed by rotating shaft 21, but the level 35 remains horizontal. The aiming device can also include the usual elevational adjustment knob 37 and the azimuth angle indicator 38. The elevation adjusting knob 37 provides forminor corrective adjustments in elevation angle when it is not desired to make such adjustments by rotating casing 15.

OPERATI'ON azimuth direction of the target. The precise adjustment for the azimuth angle of the launching tube is set by using the sight 33 and the azimuth indicator scale 38 in the usual manner. Next, the range of the target is determined by using suitable range determining equipment and when the range is known, casing is rotated by turning knurled end 15a until the predetermined range distance appears under hairline 160. By virtue of the propellant charge numerals 17a at the left side of window 16, the user of the grenade launcher also knows the number of charges of propellant necessary to project the grenadeto hit the'target. Rotating casing 15 againstthe angular position of cam face 19 with the result that follower arm 24 is turned and shaft 21 is rotated and correspondingly, the-angle of the axis of level 36 relative to the axis of launcher tube 2 is adjusted. The inter-relationship between scale 17 and the axis of level 36 is such that adjusting arms 6a so the bubble of level 36 is centered in window 38 of the level positions launching tube 2 at the proper angle of elevation to hit the target. As also shown at FIG. 2, when the range adjustment is set the elevational angle a can be read by the user of the grenade launcher through the viewing window 16.

The operation of the range table will be further clarified by the following example. After the grenade launcher is initially positioned, generally as shown at FIG. I, assume that the target is at a distance of 150 meters from the grenade launcher. The user of the grenade launcher rotates casing 15 by turning handgrip 15a until the numeral 150 appears under the hairline 16a. Range table 17 indicates that the proper angle of elevation of the launcher tube 2 to project a grenade or other missile 150 yards is 50 when the projectile is fired with a propellant charge 0. However, when casing 15 was rotated to set the range of 150 meters, the angular position of level 36 was also set and it is merely necessary for the user to adjust the bipod so the bubble of level 36 is aligned in window 39. With the bubble so aligned, the angle of elevation of launcher tube 2 is 50, and a projectile will therefore be fired meters.

While a preferred embodiment of the aiming device of this invention has been shown and described in detail, numerous changes can be made in this embodiment without departing from the scope of this invention as specified herein and defined in the appended claims.

What is claimed is:

l. A device to facilitate determining the proper angle of elevation of the launching tube of grenade throwers and the like to project a projectile a predetermined distance comprising, in combination a projectile launching tube;

means to adjust the angle of elevation of the launching tube;

a range table with its indicia on the outer surface ofa casing mounted on said launching tube for rotation;

means for manually adjusting said range table to indicate the distance a particular missile will be projected for a particular elevational angle of the launching tube;

elevation indicating means connected to said launching tube to indicate a position of the tube corresponding to a predetermined elevational angle of the tube; and

coupling means connected to said indicating means and responsive to rotation of said casing to set said elevation indicating means to an elevational position corresponding to the range distance set on said range table.

2. A device according to claim 1 wherein said elevation indicating means is connected to said launching tube to angular adjustment in response to rotation of said casing, and said indicating means includes a level angularly adjustable in a vertical plane parallel to a vertical plane including the axis of the launching tube. v

3. A device according to claim 1 wherein a base mounts thelower end of the launching tube for pivotal movement; i

a clamp sleeve surrounds the upper end of the tube;

an adjustable bipod is hingedly connected to said clamp sleeve and is adjustable to provide said means to adjust the angle of elevation of the launching tube; and

a second sleeve secured to said clamp sleeve extends around the range table of said casing in closely overlying protective relation thereto.

4. A device according to claim 3 wherein said casing projects beyond the end of said second sleeve to provide a hand grip for rotating said casing; and

said second sleeve has a transparent viewing window therein for viewing the range table on said casing.

5. A device according to claim 1 wherein said coupling means includes a cam on said casing, and a follower connected to said elevation indicating means and operable to change the angular posi tion of said indicating means in response to rotation of said casing.

6. A device according to claim wherein said cam is an axial cam at an endof said casing;

said follower is secured to a shaft supported for rotation by said launcher tube and connected to said elevation indicating means; and

which further includes means to limit the extent of rotation of said casing.

7. A device according to claim 5 wherein spring-means urge said cam follower into engagement with said cam.

Y 8. A device according to claim 3 wherein said launcher tube has an inwardly facing transverse annular shoulder;

said clamp sleeve has an inwardly extending portion presenting a downwardly facing surface engaging said shoulder; spring means between said launcher tube and clamp resiliently urge said shoulder into abutting relation with said surface to resiliently mount said sleeve relative to said launcher tube.

9. A device according to claim 1 wherein the indicia on said range table are indicative of the distance any one ofanumber of projectiles having different propellant charges will be projected by the launcher tube for a particular angle of elevation of the tube.

10. A device to facilitate determining the proper angle of elevation'of the launching tube of'grenade throwers and the like to project a projectile a predetermined distance comprising, in combination:

a. a projectile launching tube,

b. means to adjust the angle of elevation of the launching tube,

c. first and second elements mounted on said launching tube, one of, said elements including a range table with indicia and the other of said elements including an indicator,

d. means rotatably mounting one of said first and second. elements on 'said launching tube for manually adjusting said indicia and indicator relative to each other to indicate the distance a particular missile will be projected for a particular elevational angle of the launching tube,

- e. elevation indicating means connected to said launching tube to indicate a position of the tube corresponding to a predetermined elevational angle of the tube, and

f. coupling means connected to said indicating means and responsive to rotation of one of said elements to setsaid elevation indicating means to an elevational position corresponding to the range distance set on said range table.

11. A device according to claim 10 wherein one of said first and second elements is a cylindrical member mounted for rotation about said launching tube.

12..A device according to claim 11 wherein the indicia of said range table are on the outer surface of said cylindrical member; v

13. A device according to claim 12 wherein the other of said elements is a further cylinder fixedly mounted on said launching tube and including said indicator for cooperation with said indicia on the outer surface of said cylindrical member.

14..A device according to claim 11 wherein said means rotatabl mountingsaid cylindrical member on said launching ube comprises a spiral thread mounted 16. A device according to claimIS-Wherein said cam is an axial cam atone end of the said cylindrical member and said follower is secured to a shaft supported for rotation by said launching tube and connected to said elevation indicating means.

17. A device to facilitate determining the proper angle of elevation of the launching tube of grenade throwers and the like to project a projectile a predetermined distance comprising, in combination a.aprojectile launching tube,

b. means to adjust the angle of elevation of the launching tube,

c. a cylindrical member rotatably mounted on said launching tube, said cylindrical member including a range table with indicia indicating the distance a particular missile will be projected for'a particular elevational angle of the launching tube,

d. elevation indicating means connected to said launching tube toindicate a position of the tube 7 corresponding to a predetermined elevational angle of the tube, and

e. coupling means connected to said indicating means and responsive to rotation of said cylindrical member to set said elevation indicating means to an elevational position corresponding to the range distance set on said range table.

is =0: k 

1. A device to facilitate determining the proper angle of elevation of the launching tube of grenade throwers and the like to project a projectile a predetermined distance comprising, in combination a projectile launching tube; means to adjust the angle of elevation of the launching tube; a range table with its indicia on the outer surface of a casing mounted on said launching tube for rotation; means for manually adjusting said range table to indicate the distance a particular missile will be projected for a particular elevational angle of the launching tube; elevation indicating means connected to said launching tube to indicate a position of the tube corresponding to a predetermined elevational angle of the tube; and coupling means connected to said indicating means and responsive to rotation of said Casing to set said elevation indicating means to an elevational position corresponding to the range distance set on said range table.
 2. A device according to claim 1 wherein said elevation indicating means is connected to said launching tube to angular adjustment in response to rotation of said casing, and said indicating means includes a level angularly adjustable in a vertical plane parallel to a vertical plane including the axis of the launching tube.
 3. A device according to claim 1 wherein a base mounts the lower end of the launching tube for pivotal movement; a clamp sleeve surrounds the upper end of the tube; an adjustable bipod is hingedly connected to said clamp sleeve and is adjustable to provide said means to adjust the angle of elevation of the launching tube; and a second sleeve secured to said clamp sleeve extends around the range table of said casing in closely overlying protective relation thereto.
 4. A device according to claim 3 wherein said casing projects beyond the end of said second sleeve to provide a hand grip for rotating said casing; and said second sleeve has a transparent viewing window therein for viewing the range table on said casing.
 5. A device according to claim 1 wherein said coupling means includes a cam on said casing, and a follower connected to said elevation indicating means and operable to change the angular position of said indicating means in response to rotation of said casing.
 6. A device according to claim 5 wherein said cam is an axial cam at an end of said casing; said follower is secured to a shaft supported for rotation by said launcher tube and connected to said elevation indicating means; and which further includes means to limit the extent of rotation of said casing.
 7. A device according to claim 5 wherein spring means urge said cam follower into engagement with said cam.
 8. A device according to claim 3 wherein said launcher tube has an inwardly facing transverse annular shoulder; said clamp sleeve has an inwardly extending portion presenting a downwardly facing surface engaging said shoulder; spring means between said launcher tube and clamp resiliently urge said shoulder into abutting relation with said surface to resiliently mount said sleeve relative to said launcher tube.
 9. A device according to claim 1 wherein the indicia on said range table are indicative of the distance any one of a number of projectiles having different propellant charges will be projected by the launcher tube for a particular angle of elevation of the tube.
 10. A device to facilitate determining the proper angle of elevation of the launching tube of grenade throwers and the like to project a projectile a predetermined distance comprising, in combination: a. a projectile launching tube, b. means to adjust the angle of elevation of the launching tube, c. first and second elements mounted on said launching tube, one of said elements including a range table with indicia and the other of said elements including an indicator, d. means rotatably mounting one of said first and second elements on said launching tube for manually adjusting said indicia and indicator relative to each other to indicate the distance a particular missile will be projected for a particular elevational angle of the launching tube, e. elevation indicating means connected to said launching tube to indicate a position of the tube corresponding to a predetermined elevational angle of the tube, and f. coupling means connected to said indicating means and responsive to rotation of one of said elements to set said elevation indicating means to an elevational position corresponding to the range distance set on said range table.
 11. A device according to claim 10 wherein one of said first and second elements is a cylindrical member mounted for rotation about said launching tube.
 12. A device according to claim 11 whereiN the indicia of said range table are on the outer surface of said cylindrical member.
 13. A device according to claim 12 wherein the other of said elements is a further cylinder fixedly mounted on said launching tube and including said indicator for cooperation with said indicia on the outer surface of said cylindrical member.
 14. A device according to claim 11 wherein said means rotatably mounting said cylindrical member on said launching tube comprises a spiral thread mounted on said launching tube and a meshing spiral thread on said cylindrical member whereby said cylindrical member moves axially during rotation.
 15. A device according to claim 11 wherein said coupling means includes a cam on said cylindrical member and a follower connected to said elevation indicating means and operable to change the angular position of said indicating means in response to rotation of said cylindrical member.
 16. A device according to claim 15 wherein said cam is an axial cam at one end of the said cylindrical member and said follower is secured to a shaft supported for rotation by said launching tube and connected to said elevation indicating means.
 17. A device to facilitate determining the proper angle of elevation of the launching tube of grenade throwers and the like to project a projectile a predetermined distance comprising, in combination a. a projectile launching tube, b. means to adjust the angle of elevation of the launching tube, c. a cylindrical member rotatably mounted on said launching tube, said cylindrical member including a range table with indicia indicating the distance a particular missile will be projected for a particular elevational angle of the launching tube, d. elevation indicating means connected to said launching tube to indicate a position of the tube corresponding to a predetermined elevational angle of the tube, and e. coupling means connected to said indicating means and responsive to rotation of said cylindrical member to set said elevation indicating means to an elevational position corresponding to the range distance set on said range table. 